Tonga volcano eruption was largest ever recorded in over a century, scientists say

The Hunga Tonga volcano eruption in January was the largest explosion ever recorded in the atmosphere in over a century, scientists have explained.

The explosion of the volcano in the South Pacific was the biggest ever recorded by modern geophysical equipment, said a study published last week in the journal Science.

The atmospheric pressure wave produced by Hunga Tonga – which erupted on 15 January – was said to be about a thousand times more powerful than the atomic bomb dropped by the US on Hiroshima during the Second World War, according to Nasa.

The new study said the explosion also lasted four times longer than the biggest nuclear weapon explosion.

Only the 1883 Krakatoa eruption created a shockwave of a similar scale, said the international team of researchers, including those from the University of Reading in the UK.

“Reviewing data from recording equipment has revealed the sheer scale of this once-in-a-century eruption, which dwarfed every previously recorded explosion created by man or nature,” said Giles Harrison, an atmospheric physicist at the University of Reading and co-author of the study.

“It is amazing that cloud on a quiet Saturday evening in the UK was disturbed by a volcano in Tonga (sic),” Dr Harrison said.

The Hunga Tonga eruption created a pressure wave that travelled around the world four times over six days – about the same for Krakatoa – showed barometer readings.

Audible sound from the Tonga eruption was reported 10,000km away in Alaska, compared to historical records of the Krakatoa explosion being heard 4,800km away from the event centre.

The explosive eruption generated a broad range of atmospheric waves observed globally by various ground-based and spaceborne instrumentation networks.

The pressure wave from the volcano was also recorded by the International Monitoring System set up to monitor compliance with the Comprehensive Nuclear Test Ban Treaty.

Measuring the Tonga eruption using new technology has given scientists the ability to learn from the event what they could only speculate about Krakatoa.

“The only way people actually measured Krakatoa was with weather instruments – barometers – which measure the very low frequency changes in the atmosphere,” said Stephen Arrowsmith, a co-author of the study from Southern Methodist University in the US.

“They didn’t have satellites, and they didn’t have seismometers around the world. They didn’t have infrasound sensors that were in the atmosphere, or acoustic sensors within the ocean. So, this is actually the first time that an event like this has been recorded in this way,” Dr Arrowsmith added.

Scientists believe the Tonga eruption will be studied for decades to come to improve predictive models due to its vast and widespread effects seen from the oceans to the upper atmosphere.